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Built for those who build the Web. Introducing the only browser made for developers.

Built for those who build the Web

Introducing the only browser made for developers like you.

Design, build and debug the Web without ever leaving your browser with the new Firefox Developer Edition!

Firefox Developer Edition automatically sends feedback to Mozilla.

Designed for developers

The only browser made just for developers, Firefox Developer Edition was created with your workflow in mind. Build, test, scale and more all from one place, for the first time ever.

Debug any browser

Inspect and debug your app across any browser or device with Valence — a powerful, pre-installed extension that you’ll only find in Firefox Developer Edition.

Pixel-perfect coding

Target screen sizes with the Responsive Design View and tweak your CSS on the fly with the built-in Style Editor for pixel-perfect coding.

All your favorite dev tools and more

Firefox Developer Edition brings your core dev tools together with some powerful new ones that will extend your ability to work across multiple platforms from one place. It’s everything you’re used to, only better. And only from Firefox.

WebIDE

Develop, deploy and debug Firefox OS apps directly in your browser, or on a Firefox OS device, with this tool that replaces App Manager.

Learn more about WebIDE

Responsive Design View

See how your Website or Web app will look on different screen sizes without changing the size of your browser window.

Learn more about Responsive Design View

Valence

Develop and debug your apps across multiple browsers and devices with this powerful extension that comes pre-installed with Firefox Developer Edition.

Learn more about Valence

Web Audio Editor

Inspect and interact with Web Audio API in real time to ensure that all audio nodes are connected in the way you expect.

Learn more about Web Audio Editor

Page Inspector

Examine the HTML and CSS of any Web page and easily modify the structure and layout of a page.

Learn more about Page Inspector

Web Console

See logged information associated with a Web page and use Web Console to interact with Web pages using JavaScript.

Learn more about Web Console

JavaScript Debugger

Step through JavaScript code and examine or modify its state to help track down bugs.

Learn more about JavaScript Debugger

Network Monitor

See all the network requests your browser makes, how long each request takes and details of each request.

Learn more about Network Monitor

Style Editor

View and edit CSS styles associated with a Web page, create new ones and apply existing CSS stylesheets to any page.

Learn more about Style Editor

Choose Firefox

Welcome to Firefox Developer Edition

Developer Tools

The most complete browser made just for developers, Firefox Developer Edition has every dev tool you’ll need built right in.